The invention relates to a watch, in particular a dive watch, having a movement which is arranged in a watch case and can be used to drive an hour hand via an hour tube, and a minute hand and, if appropriate, a second hand via a minute tube in a fashion sweeping over a dial, as well as having a pressure detecting device for detecting the ambient pressure outside the watch case and a display for representing the detected pressure values.
It is known in dive watches to detect the ambient pressure by means of electric or electronic sensors and to convert it in an electronic evaluation device into signals for driving a dive depth display. Both the detection and the representation of the ambient pressures require a battery as power supply. If the battery performance drops, the dangerous situation arises for the diver that the sensors and the display can still function to a certain extent, with the result that the user assumes he has a fully functional dive watch. However, because of the no longer adequate power supply both the values detected and the values displayed are incorrect.
It is possible thereby for situations which endanger the diver""s health or even life-threatening situations to occur, for example due to diving deeper than intended or ascending more rapidly than permissible.
It is therefore the object of the invention to create a watch of the type mentioned at the beginning in which these disadvantages of known watches are avoided.
This object is achieved according to the invention there is arranged in the watch case a mechanical pressure transducer to which the ambient pressure outside the watch case can be applied and by means of which a mechanical depth measurement mechanism of a mechanical display can be driven. Since none of the watch components for displaying the dive depth depends on a supply of electric or mechanical power, all the disadvantages based on reduction in power and power loss are avoided. The depth display of the watch is completely autonomous and thus always operational and fully functional.
In a simple design, the mechanical depth measurement mechanism can have a display shaft which can be rotatably driven by the pressure transducer and carries a depth hand which can sweep over a depth scale.
A low overall size is achieved by virtue of the fact that the display shaft is arranged coaxially with the hour tube and minute tube, and the depth scale is arranged on the dial.
If the scale division of the depth scale corresponds to the scale division of the minute scale, the display on the depth scale can be taken in just as quickly and easily as is already usual from habit in the case of minute scales on analog watches.
A further contribution to reducing the overall size results when the display shaft projects coaxially through the hour and minute tubes and, if appropriate, the second tube.
The pressure transducer can be connected to the environment via a measuring opening.
If a measuring opening in the watch case is constructed such that it can be closed manually in order to connect the pressure transducer to the environment, a depth measurement can consciously be performed only if the measuring opening is opened for this purpose. If the watch is also used in other regions in which substantially higher pressures prevail than for the measuring range suitable for the pressure transducer, the pressure transducer is protected by closing the measuring opening.
As an alternative to this, a closing device of the measuring opening can be constructed as a pressure-reducing valve by means of which the measuring opening can be closed upon overshooting of a specific ambient pressure.
In a simple design, the measuring opening can in this case be closed manually by a screwed crown.
If it is possible to apply the ambient pressure outside the watch case to the mechanical pressure transducer via an incompressible medium, it is impossible for it to be damaged by pollutants and aggressive substances such as, for example, also sea water, which reach the pressure transducer from outside.
The incompressible medium can be a liquid such as, for example, water, in particular distilled water, or oil.
In a simple way, the ambient pressure can be applied to the incompressible medium via a movable wall.
If in this case the movable wall is a diaphragm which is clamped permanently and tightly at its circumferential edge on a housing, the result is simultaneously to achieve a tight separation of the region filled with the incompressible medium from the environmental region.
The purpose of transmitting the ambient pressure directly, and thus without impairment, to the pressure transducer is furthered when there is constructed in the watch case a measuring opening which serves for the application of the ambient pressure to the pressure transducer and leads to a chamber which is filled with the incompressible medium and of which one wall is the movable wall to which the ambient pressure can be applied.
A design which is particularly simple and not prone to defects consists in that the pressure transducer is an annular spring pressure gauge with an annular Bourdon spring of which one end is fastened on the watch case and is connected to the measuring opening and of which the other end, which can be freely swiveled radially, can drive in a movable fashion the depth measurement mechanism by means of which the pivoting movement of the free end of the Bourdon spring can be converted into a movement which can drive the display shaft rotatably.
For the purpose of protection against overloading, the capacity of the free end of the Bourdon spring to swivel radially can be limited by stops.
It is preferable for the Bourdon spring to be arranged surrounding the movement in the watch case, with the result that only a small overall space is required. If, in this case, the Bourdon spring is arranged with play in an annular chamber of the watch case, the walls of the annular chamber forming the stops, the Bourdon spring is simultaneously protected against overloading in conjunction with a small overall size.
The purpose of directly transmitting the ambient pressure to the Bourdon spring is furthered when the interior of the Bourdon spring is connected to the chamber via the measuring opening and is filled with the incompressible medium. In this case, the chamber with the movable wall serves at the same time as a volume-equalizing chamber for the volume of the Bourdon spring, which increases with rising pressure owing to widening of the curvature.
If the movable wall can be subjected to the action of a manually displaceable pusher in a fashion reducing the volume of the chamber, it is possible by applying a specific force to the pusher to simulate a specific dive depth, and thus to check the functionality and accuracy of the display.
Moreover, the pusher forms a support surface for the movable wall, which is constructed, in particular, as a diaphragm.
In order to define the position of the movable wall under standard ambient pressure, the capacity of the pusher to be displaced in the direction of which the volume of the chamber is increased is limited by a stop. If the stop can be set adjustably in the displacement direction of the pusher in this case, the pressure transducer can be adjusted by the pusher.
For the purpose of simple assembly, the chamber and/or the pusher can advantageously be arranged in a crown.
Since the position of the depth hand depends only on the position of the end piece, fixed to the case, of the Bourdon spring, in the case of changes in air pressure, an adjustment of the hand already comes about which falsifies the actual dive depth during a dive. In order to be able to set the depth hand exactly to zero before a dive, the end of the Bourdon spring fastened on the watch case can be adjusted radially.
For this purpose, in a simple construction the end of the Bourdon spring is fastened on the watch case via a shaft projecting radially out of the watch case, the shaft being adjustable in the direction of its longitudinal extent. For the purpose of adjusting the shaft easily, it is possible for the shaft to be guided displaceably in a crown bush which is firmly connected to the watch case and is provided with a thread on which there is arranged a union nut on which the free end of the shaft is supported. In order to permit fine adjustment, the thread can be a fine thread. The play in the thread is eliminated by virtue of the fact that a spring force is applied to the shaft axially against the union nut.
In order to connect the interior of the Bourdon spring to the environment, the shaft has an axial bore one of whose ends is connected to the environment and the other of whose ends is connected to the interior of the Bourdon spring.
If the union nut is constructed in a pot-shaped fashion and has a cover which covers the opening region, directed towards the environment, of the axial bore of the shaft, and in which one or more through bores of small cross section are constructed, the cover forms a support for the shaft. The through bores of small cross section prevent the ingress of contaminants.
The end of the shaft on the Bourdon spring end can be mounted with a transverse bore pivotably on a joint hollow screw, the axial bore of the shaft opening into an axial bore of the joint hollow screw, and the axial bore of the joint hollow screw, which is firmly connected to the Bourdon spring, opening into the Bourdon spring. The relative swivelings between the end of the Bourdon spring and shaft can be performed without stresses between these parts.
In order to permit the radial movement of the end of the Bourdon spring when the shaft is applied, the Bourdon spring can be fastened in the region of the joint hollow screw on one end of the pivoting arm whose other end can be pivoted about a pivoting axis which is arranged firmly on the watch case and extends parallel to the longitudinal axis of the joint hollow screw.
In order to be able to adjust the mechanical depth measurement mechanism and the depth hand in a simple way, the mechanical depth measurement mechanism can be arranged on the bottom side of the watch case, which is opposite the dial and can be closed by an openable case bottom. The depth measurement mechanism is thus accessible independently of the movement.
In this case, the display shaft preferably projects through the movement.
For the purpose of driving the depth measurement mechanism, the free end of the Bourdon spring can be pivotably connected via an articulated rod mechanism to a lever of a saw segment by means of which a drive pinion of the display shaft can be driven rotatably. In this case, the articulated rod mechanism is preferably pivoted with its one end at the free end of the Bourdon spring and with its other end at the free end of the saw segment lever.
In order to be able to compensate manufacturing tolerances in the Bourdon spring, the articulated rod mechanism can be set in a fashion varying its length. For this purpose, the connection of the articulated rod mechanism to the lever 26 of the saw segment is preferably guided displaceably and can be fixed in the longitudinal extent of the articulated rod mechanism.
In a simple way, it is possible in this case for the lever of the saw segment to have an elongated hole into which there project two guide pins which are arranged on the articulated rod mechanism at a smaller spacing from one another in the longitudinal extent of the articulated rod mechanism than the length of the elongated hole, it being possible for a fixing screw to be screwed in a fashion penetrating the elongated hole into a threaded hole in the lever of the saw segment, and to be pressed with its screw head on the lever of the saw segment against the articulated rod mechanism.
For the purpose of adjustment, a pin which is arranged such that it can rotate parallel to the guide pin on the lever of the saw segment and has an eccentric head can project into a bore in the articulated lever mechanism.
If a pivotably arranged spring-loaded resetting saw segment engages in the drive pinion and can be applied in order to move the drive pinion rotatably in the depth direction, the result is immediate resetting of the depth hand upon surfacing after a dive. At the same time, the saw segment remains with the flanks of its teeth always in the same direction of rotation bearing against the tooth flanks of the drive pinion, with the result that there is no tooth play to be overcome in the case of a reversal of the pivoting movement of the saw segment level upon resurfacing. This contributes to the accuracy of the depth display.
If the aim is also to display the maximum depth of a dive in a simple way, a non-return hand indicating the maximum depth of a dive can be driven pivotably in the depth direction by the pressure gauge or the depth measurement mechanism or the depth hand. Upon resurfacing, the non-return hand then remains in the position of the maximum dive depth reached.
It is possible in a simple way for the depth hand to have a driver by means of which the depth hand can strike against the non-return hand and the latter can be moved in the depth direction. A special drive for the non-return hand is therefore not required.
If the non-return hand can be driven pivotably about an axis coaxial with the rotation axis of the depth hand, it being the case that in a simple design the non-return hand is arranged on a non-return hand shaft or on a non-return hand tube surrounding the display shaft, the non-return hand and depth hand indicate their measured values on the same depth scale.
In order for the non-return hand to be able to return to its normal position after displaying a maximum depth, the pivoting movement of the non-return hand can be locked against the depth direction by a releasable latching device. In this case, in a simple design the pivoting movement of the non-return hand can be locked by a pawl-type lock.
The non-return hand shaft or the non-return hand tube can have a locking disk with a row of teeth which are arranged running around radially and in the tooth spaces of which a locking pawl can engage in a locking fashion against the depth direction.
For this purpose, it is possible, in a simple way, to construct the locking disk on its radially circumferential edge with a row of saw teeth of which the teeth are directed against the direction of rotation of the non-return hand toward depth.
For ease of movement of the locking pawl, the locking pawl can be pivotable about a pivoting axis.
In order to be able to reset the non-return hand the locking pawl can be acted upon manually in the unlocking direction, this being possible in a simple design by virtue of the fact that the locking pawl can be acted upon in the unlocking direction by an actuating slide which projects from the watch case with its one end such that it can be acted upon manually, or which can be acted upon manually by a pusher. The non-return hand can thus be reset in a simple and quick fashion. In order to define the position of the non-actuating locking slide, the unlocking slide can be spring-loaded against the direction in which the locking pawl can be acted upon.
If the non-return hand is resiliently biased against the depth direction with respect to the depth hand, it is automatically reset against as far as the stop on the depth hand after release of the latching device. In a simple way which saves overall space, it is possible, for this purpose, to provide that a biased spiral spring surrounding the display shaft is permanently arranged with its one end on the display shaft and with its other end on the non-return hand shaft or the non-return hand tube or the locking disk.
In order to prevent the locking pawl braking the locking disc, and thus to prevent a jerky movement of the non-return hand, in each case a locking pawl can be arranged at a spacing one from another in the circumferential direction of the locking disc on each lever arm of a two-arm lever which can be pivoted freely about a pivoting axis parallel to the axis of rotation of the locking disc, it being possible, upon rotation of the locking disc in the depth direction for the locking nose of one locking pawl to be moved, sliding along the tooth flank, out of a tooth space of the row of saw teeth and thereby for the two-arm lever to be pivoted in such a way that in the process the locking nose of the other locking pawl can be moved into a tooth space of the row of saw teeth.
For the purposes of decoupling the two locking pawls easily after a dive, the actuating slide can be displaceably guided approximately radially relative to the axis of rotation of the locking disc and can carry the pivoting axis of the two-arm lever.